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Micro Wirelessly Powered LED Modules - Possible?

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LAN_403

GlowPros

Sat Feb 07 2015, 07:01PM

Registered Member #54354 Joined: Tue Jan 27 2015, 04:10AM
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Posts: 10

I appreciate all the input - if someone feels they have a potential solution that's worth a shot, let me know.

Of course, I may not be the best at attempting to put it all together either.

Dr. Slack

Sat Feb 07 2015, 08:11PM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

The distance you can acheive for reasonably efficient wireless power, without using exotic materials, is roughly the size of the transmitting and receving antenna. If you tune the ends with high Q circuits, then you might get up to a few times in distance. Beaming power requires wavelength several times smaller than the dimensions of your transmitter, so microwaves or light.

You won't acheive the distances you want, with the sizes you want, and by an order of magnitude or two.

GlowPros

Sat Feb 07 2015, 08:14PM

Registered Member #54354 Joined: Tue Jan 27 2015, 04:10AM
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Posts: 10

What about this mentioning of using light or ir to transmit the power?

Patrick

Sat Feb 07 2015, 11:38PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

coupling and directionality are typically the problems. There is a Japanese professor who has invented a microwave IC capable of super directional high power transmission. it was tested on the Science or Discovery channel from helicopters over Hawaii since the FCC was weak in the knees. I cant remember the name of the professor of TV episode, as this was about 8-10 years ago.

Its probably out of our reach anyway.

Carbon_Rod

Sun Feb 08 2015, 06:03AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
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Posts: 1155

@Dr. Slack
Seems like $5 worth of parts to blink the LED could be ridiculously inefficient with an on-time that would be proportional to the Tx ERP and inverse square laws. Ideally, with 10% on-time we achieve around 10mA constant drain or around 0.033 Watt/hours needed.

Using a calculator for the RF Tx station I assumed:
3 Watt ERP, 2 m proximity distance, and ignored the FCC at great peril.

And conclude at a radial distance of 2 m we achieve 0.15 V/m, 0.04 A/m, and around 0.06 mW/cm^2.
Assuming a 1/4 wave antenna at ~2.4GHz, we get around a 12.5cm/4 area receiving. Therefore, our available output becomes:
(0.06 mW/cm^2*(0.001 watts/mW))*12.5cm/4=0.0002 watt/hrs ideal

In conclusion, a 3 watt transmitter is roughly 180 times less powerful than required.
A single RF system is indeed unlikely to be feasible...
but around 200 slots around the band may work though... LOL

A solar cell (some work well in IR) would be much cheaper...

Andy

Sun Feb 08 2015, 08:02AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Posts: 874

Hi Glopos, the below should work, will it type of worked for me, not sure how to make a constant current from it.

1423382539 4266 FT168856 Img 20150208 210216

The 1uS pulse works out to be 1Mhz with depending how you build the bottom plates will have a capacitance value say about 1-10fF at 1kv @1Mhz should send the ac voltage throught the capacitor to the plates at the top assuming the air is the diletic, and assume you raise the potent of earth anduse it as a large plate make about 3-5volt between the two reciver plates, with resonances to raise the voltage to a higher value.

The distance horzintal should be about 10meters vertical 1meter , making a lower pulse voltage, you will need small pulse widths.

GlowPros

Sun Feb 08 2015, 12:28PM

Registered Member #54354 Joined: Tue Jan 27 2015, 04:10AM
Location:
Posts: 10

Hello - thank you for the diagram! However I'm ashamed to say I am not that savvy when it comes to reading schematics... I'd love to give this a try but if you don't mind telling me what is all there or what I'd need to do it, that would be great :)

BigBad

Mon Feb 09 2015, 04:10PM

Registered Member #2529 Joined: Thu Dec 10 2009, 02:43AM
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Posts: 600

This system looks like it would be horribly inefficient, but it would probably get more efficient if you had a lot of receivers in the space.

Small receivers can only accept a small amount of power, but the transmitter is essentially (kinda) filling space with energy that can be picked up. If it's not being received, it's lost as heat in the transmitter, and some is radiated away.

At least, that's how it would work if you're using capacitive or inductive coupling.

Patrick

Mon Feb 09 2015, 04:46PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

this is what i meant, the professor has what i think to be a monolithic GHz IC, i remember the episode, this professor was so worried about his precious IC he kept his finger on it to see if it was too hot.

GlowPros

Mon Feb 09 2015, 04:56PM

Registered Member #54354 Joined: Tue Jan 27 2015, 04:10AM
Location:
Posts: 10

If someone can help me make the circuit work and run multiple led "receivers", I would be willing to compensate them...

I feel I'm skilled and pretty handy at building things, but I tend to work best from specific directions or demonstrations. :)

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